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Biomedical subjects

W Precht

Publications and source records attributed to W Precht.

122 records · Page 7Linked to original sources
PubMed1969

Preferred centripetal conduction of dendritic spikes in alligator Purkinje cells.

Dendritic action potentials in alligator Purkinje cells tend to have a unidirectional preference which favors centripetal over centrifugal propagation. This unidirectional tendency funnels the peripherally evoked dendritic spikes into the lower dendrites and soma of these cells, and it allows the peripheral dendritic branches to operate to a certain extent as partially independent functional units.

Action Potentials↗
PubMed1967

Cerebellar Purkinje cell projection to the peripheral vestibular organ in the frog.

Neurones located 200 to 300 microns from the surface of the auricular lobe of the frog cerebellar cortex, and identified as Purkinje cells, were activated antidromically from the eighth cranial nerve. A parallel anatomical study confirmed the existence of this projection. On the basis of these findings the existence of a cerebello-vestibular efferent system is postulated, the precise significance of which is as yet unclear. However, since Purkinje cells in other species have an inhibitory action on their target cells, the Purkinje efferent system to the vestibular organ may have an action similar to that ascribed to the olivo-cochlear bundle upon the cochlea, that is, to serve as an inhibitory control system.

Action Potentials↗
PubMedDate not supplied

Vestibular nuclear neuron activity in chronically hemilabyrinthectomized cats.

The activity of central vestibular neurons (Vn) of the horizontal canal system was recorded in chronically hemilabyrinthectomized cats and compared with that of labyrinth intact animals. In both groups the cerebellar vermis was removed in order to assess the efficacy of the vestibular brainstem commissure alone by means of polarizing currents applied to the labyrinths. Experiments were carried out under Ketamine anaesthesia. In control animals the mean resting rates of type I and type II Vn measured 22.4 +/- 14.0 and 27.5 +/- 14.6 imp/s respectively, and the type I responses occurred ca. 3 X more frequently than type II. In the lesioned animals a drastic reduction of the number of type I responses was found on the deafferented side, while that on the intact side remained normal. The resting rates of type I Vn on the two sides did not differ significantly from each other but were significantly lower than those of control animals. In contrast, type II responses were present on the deafferented side, but almost completely missing on the intact side. Applying polarizing stimuli in control animals, it was found that both labyrinths have similar weight in driving Vn. In lesioned animals, no major changes in the efficacy of the commissural path were found when polarizing stimuli were applied to the intact side. It is concluded that vestibular nerve section causes a severe loss of type I responses in the vestibular nuclei on the side of the lesion which apparently is not compensated by an adaptive change in the commissural path and, therefore, may be mainly responsible for the VOR asymmetry observed concomitantly.

Afferent Pathways↗